1. Field of the Invention
The present invention relates to a thin film forming equipment and a thin film forming method used for correcting defects in a substrate having a plane pattern structure such as a photomask, liquid crystal substrate or a like.
2. Description of the Related Art
AlaserCVD (Chemical Vapor Deposition) method is disclosed in U.S. Pat. No. 4,801,352 in which a thin film is formed at a local place on a substrate by radiating a specified gas introduced at the local place on the substrate with a laser to decompose the substrate.
FIG. 4 is a cross-sectional view of conventional thin film forming equipment. As depicted in FIG. 4, a gas window 52 is mounted on a substrate 51. The gas window 52 is so constructed that there is a small clearance (for example, of 0.5 mm) between an upper face of the substrate 51 and a lower face of the gas window 52. The gas window 52 is provided with a gas retention chamber 53, a gas introducing section 54, a gas exhausting section 55 and a laser window 56. The gas retention chamber 53 is a chamber for the retention of CVD materials such as gases of organic metal compounds or a like. The gas introducing section 54 is a section used for introducing the CVD materials into the gas retention chamber 53. The gas exhausting section 55 is composed of ring-shaped trenches 55a formed in the circumference of the gas retention chamber 53 and of an exhausting section 55c connected through a hole 55b, which is used for exhausting the gas discharged from the gas retention chamber 53. The laser window 56 is used for radiating the CVD materials staying in the gas retention chamber 53 with the laser to decompose them.
The substrate 51 is held by the holder 57. That is, the substrate 51 is held by hanging an end portion of the substrate 51 on a step section 57a of the holder 57. A transmitting illuminating source 58 is used to check a quality of films formed by the CVD process. A lens 59 is used for collecting laser light. A flow of gases used as the CVD materials is shown by arrow marks in FIG. 4.
However, following problems arise when the gas retention chamber 53 of the above equipment is positioned in the proximity of the end portion of the substrate 51 and the thin film is formed in the proximity of the end portion of the substrate 51. Since there is a step area between the upper face of the substrate 51 and the upper face of the holder 57, if the gas retention chamber 53 is positioned in the proximity of the end portion of the substrate 51, the gas is suctioned from the exhausting section 55c through the ring-shaped trench 55a and the gas exhausted from the gas retention chamber 53 is to be ejected, air currents are influenced at the step area and the air flows into the gas retention chamber 53 as shown by the arrow xe2x80x9caxe2x80x9d in some cases, causing degradation in the quality of the film formed by the CVD process.
Also, there are some cases in which gases used as the CVD materials are not completely ejected through the trench 55a from the exhausting section 55c. In some cases, gases used as the CVD materials leak to surroundings.
In view of the above, it is an object of the present invention to provide a thin film forming equipment and a method for forming thin films which are capable of forming the thin film of high quality and of effectively preventing gases used as CVD materials or a like from leaking to surroundings at a low cost.
According to a first aspect of the present invention, there is provided a thin film forming equipment including:
a substrate;
a substrate holding device used to hold the substrate;
a device used to provide atmospheric gas to a surface of the substrate held by the substrate holding device; and
whereby an upper face of the substrate held by the substrate holding device and an upper face of the substrate holding device are almost on one plane.
In the foregoing, a preferable mode is one wherein the substrate holding device has a cover body which is disposed in an area surrounding the substrate held by the substrate holding device and wherein an upper face of the cover body and the upper face of the substrate are almost on one plane.
Also, a preferable mode is one wherein the substrate holding device is provided with a trench along a circumference of the held substrate and the atmospheric gas is able to be ejected through the trench.
Also, a preferable mode is one wherein a sheet is provided at a boundary between the held substrate and the substrate holding device.
Furthermore, a preferable mode is one wherein the thin film forming equipment provides the atmospheric gas to a surface of the substrate held by the substrate holding device and forms the thin film on the substrate by decomposing the atmospheric gas and wherein the thin film forming equipment further includes gas introducing means for introducing the atmospheric gas, a gas retention chamber for retention of the introduced gas using the gas introducing means, gas discharging means for discharging gas ejected from the gas retention means and laser radiating means for decomposing gas staying at the gas retention chamber by laser irradiation.
According to a second aspect of the present invention, there is provided a method for forming a thin film on a substrate by decomposing gas introduced to a surface of a substrate held by a substrate holding device including a step of preventing the gas introduced to the surface of the substrate from being influenced by outside air.
According to a third aspect of the present invention, there is provided a method for forming a thin film on a substrate by introducing gas to a surface of a substrate held by a substrate holding device, by radiating the introduced gas with laser, by decomposing the introduced gas and then by suctioning and discharging decompositional by-products, including a step of preventing the gas introduced to the surface of the substrate from being influenced by outside air.
In the foregoing, it is preferable that the upper face of the substrate and the upper face of the substrate holding device are almost on one plane to prevent gas introduced on the substrate surface from being influenced by outside gas.